Flash
User Page
The bootloader uses the flash
User page is used to store the I/O conditions that determine which of the USB
DFU ISP and the application to start at the end of the boot process.
Bits
of the Flash User Page |
Name |
Description |
7:0 |
ISP_CRC8 |
CRC8 on the bootloader User
page configuration word with polynomial: P(X) = X^8+X^2+X+1. This CRC is used to check the
validity of this configuration word. Wizard compute this value |
15:8 |
ISP_IO_COND_PIN |
The GPIO pin number to test
during the boot process to know which of the USB DFU ISP and the application
to start. The wizard will give possible
values are depending on 1st page selection: -
GPIO
from 0 to 109 for AT32UC3A QFP144 -
GPIO
from 0 to 69 for AT32UC3A QFP100 -
GPIO
from 0 to 43 for AT32UC3B QFP64 -
GPIO
from 0 to 27 for AT32UC3B QFP48 |
16 |
ISP_IO_COND_LEVEL |
Active level of ISP_IO_COND_PIN
that the bootloader will consider as a request for starting the USB DFU ISP: -
0
for GPIO low level -
1
for GPIO high level |
31:17 |
ISP_BOOT_KEY |
Boot key = 494Fh. This key is
used to identify the word as meaningful for the bootloader. |